Estimating nitrogen transfer by foliar 15N-labelling in legume – non-legume associations

We examined the basis for estimating the transfer of legume N to companion cereals or grasses in intercropping or pature systems using the foliar ¹⁵N-labelling technique. Published data from three pot experiments were used to illustrate different methods for estimating N transfer. Yield-dependent and yield-independent methods based on measurement of the ¹⁵N enrichment of the whole legume biomass at harvest overestimate N transfer. Estimates of N transfer using a yield-independent method based on the ¹⁵N enrichment of the legume roots at harvest were inconsistent with estimates based on the isotopic composition of the whole plant. We propose a new mathematical concept for estimating the transfer of legume N based on measurement of the ‘mean pool abundance’ of the legume biomass during the period of N transfer. Received: 7 January 1996     

豆科植物在生态恢复方面的应用研究进展

豆科植物适生范围广、抗逆性强,在此对其在生态恢复方面从矿区植被恢复、石质边坡生态复绿、保持水土和土地持久生产力恢复等进行了概述,并对其应用前景做了展望。     

Elaboration of amylase activity and changes in paste viscosity of some common Indian legumes during germination

The effect of germination upto 120 hours on malting loss, amylase activity and viscosity of nine common Indian legumes was investigated. The amylase activity increased on progressive germination in all legumes, the increase being particularly high for green gram, horse gram, moth bean and black gram. Malted samples had lower cooked paste viscosity than native ones. Samples with high amylase activity exhibited proportionately lower viscosity. Maximum reduction in viscosity was observed in green gram, followed by moth bean, horse gram, black gram and cowpea within 48 hours of germination. Malting losses ranged between 12 to 27 percent over a period of 48 hours in all legumes. Germination beyond 48 hours resulted in considerably higher malting losses without much effect on viscosity.     

Leaf protein content and yield of some Indian legumes

Eighty three leguminous species including crop plants, weeds and trees have been screened for their content of leaf protein as well as extractabilities of leaf protein, total N and protein N. Leaves ofCrotalaria sericea Retz. showed the heighest values for extractabilities of LP and protein N as well as total N content in leaf protein.Abbreviation LP leaf protein     

Low levels of ferredoxin, ATP and leghemoglobin contribute to limited N2 fixation of peas (Pisum sativum L.) and alfalfa (Medicago sativa L.) under S deficiency conditions

Sulphur (S) has become a major limiting factor for plant production in industrial as well as in remote industrial rural areas. Limitation of S can reduce legume N₂ fixation by affecting nodule development and function. In pot experiments with pea (Pisum sativum L.) and alfalfa (Medicago sativa L.), we investigated the influence of S on growth, ferredoxin, ATP and leghemoglobin concentrations. Addition of 200 mg S pot⁻¹ increased yield of shoots, roots and nodules of both plant species significantly. However, the influence of S on nodule yield formation was most pronounced. Pea and alfalfa roots were found to have higher S concentrations than shoots and being up to 2.9 times the S concentration in the shoots of peas under S-sufficient conditions. Sulphur addition also increased N₂ fixation significantly. The ferredoxin concentration in bacteroids of root nodules of pea was increased significantly by S only 10 weeks after planting and in bacteroids of root nodules of alfalfa 10 and 17 weeks after planting, while on per pot base the amounts of ferredoxin were higher throughout the experimental period of time. The ATP concentration of bacteroids of root nodules of both plant species as well as of mitochondria of root nodules of pea were significantly higher with optimum S supply. The effects of S deficiency on N₂ fixation are likely to be caused by the shortage of ferredoxin and ATP. The amount of leghemoglobin was reduced in comparison to nodules of the S-sufficient plants.     

Contents of total protein, L-canavanine and condensed tannins of the one-flowered vetch (Vicia articulata Hornem.) collection of the Bank of Plant Germplasm of Cuenca (Spain)

A total of 125 accessions of one-flowered vetch (Vicia articulata Hornem.) mostly from the Iberian Peninsula have been analysed for total protein, L-canavanine and condensed tannins. It was observed a high variability in the composition: the protein content ranged from 18.20 to 30.07%, L-canavanine from 0.27 to 0.67%, and condensed tannins from 0.13 to 0.35%, which indicates a scarce domestication of the crop. The inclusion of the seeds into a diet to non-ruminants should be limited to marginal percentages because of the contents of L-canavanine and it suggests that a reduction of this compound by breeding should be encouraged. The protein and the L-canavanine contents showed a low and positive significant correlation (r = 0.55, P < 0.001), which complicates the selection of seeds having simultaneously low L-canavanine and high protein contents. On the other hand, no correlation between protein and condensed tannins or between L-canavanine and condensed tannins was observed. There was a poor relationship between the origin and the composition of the accessions and only the protein content was able to discriminate among the regions.     

Effect of supplementation of fresh and ensiled clovers to ryegrass on nitrogen loss and methane emission of dairy cows

Two experiments were carried out to compare white clover with red clover as supplementation to ryegrass, in ensiled and fresh form, for differences in nitrogen loss and methane emission by dairy cows. In experiment 1, fresh ryegrass was mixed with fresh white (WF) or red clover (RF) (60/40 on dry matter basis). Experiment 2 involved similar mixed diets in ensiled form (WS and RS, respectively), and two ryegrass silage diets, without (GS) or with supplementary maize gluten meal (600 g protein/kg DM; GS+). Barley was supplemented to meet the calculated requirements for milk production. The type of clover did not affect crude protein (CP) intake in experiment 1. In experiment 2, the highest CP intakes were observed for cows on the GS+ diet (P < 0.05), followed by the WS and RS diet, compared to the GS diet. Within experiments, no treatment effects occurred for intake of digestible organic matter, milk and milk protein yield, while milk urea and urine N excretion mostly reflected the differences in CP intake in experiment 2. The highest absolute N excretions (P < 0.001) occurred with the GS+ diet, compared to the other diets. Per unit of N intake, a tendency for highest urine N losses with GS+ was still noticeable. The slurry characteristics were not affected by clover type during storage in experiment 1. In experiment 2, initial treatment differences in ammonia-N levels (P < 0.01) in the slurry were still observed after 8 weeks of storage. Clover supplementation, but not clover type, slightly enhanced gaseous N losses per cow per day in relation to GS, but not as much as GS+ (+53%). Gaseous N losses relative to milk N yield were slightly lower (P < 0.1) with fresh red clover compared to white clover, a trend not apparent in experiment 2 with silages where levels were elevated with GS+. Methane emissions were not affected (P > 0.05) either by clover supplementation or by clover type in both experiments. This study illustrates that the white and red clovers investigated were widely similar for their effects on N losses and methane emission in dairy cows. Our findings imply that supplementation of white or red clover to a high-protein ryegrass could enhance nitrogen losses to the environment, and would not be beneficial in terms of reducing methane emissions.     

Acceptability of supplementary foods based on popped cereals and legumes suitable for rural mothers and children

Eight types of supplementary foods based on popped cereals (wheat, ragi, bajra and sorghum) blended with legumes (soy and bengalgram) and fortified with essential vitamins and minerals were developed on a pilot plant scale. Four of the supplements were prepared with cereals, soy flour (SF) and bengal gram (BG) dhal and the other four were prepared with combinations of cereals and SF. These blends were mixed with jaggery (obtained by boiling juice out of sugarcane) syrup and pressed into compact form. One hundred gram portions of these foods provided 370 ± 20 kilocalories and 11 ± 1 g protein. Moisture, crude protein, total carbohydrates, total lipids, ash, dietary fiber and energy contents, of all the developed supplements were within the ranges prescribed by the Indian Standards Institute for processed weaning foods and could satisfactorily meet one-third of the Recommended Dietary Allowance (RDA) of these nutrients per day for preschool children. Organoleptic evaluation and feeding trials revealed that the foods were well accepted by rural mothers and children.     

南方果茶园生草栽培草种研究进展

针对生草栽培需要注重掌握的草种特性,回顾中国南方果茶园生草栽培主要选择应用的草种(白三叶草、柱花草、圆叶决明、罗顿豆、铺地木兰、百喜草、高羊茅、多年生黑麦草及糙叶丰花草)的研究进展情况,归纳出草种研究存在开发与筛选不足、研究与应用不接轨、生草建植存在困难、育种研究不够重视4个方面的问题,提出草种开发筛选应遵从外在植物学...